Dehairing and bating of skins and hides



Patentedoct. 12, 1937 narmmmo aim ENT OFFICE Leo Wallerstein and JuliusHanmnnller, New York, N. Y., assignora to Waller-stein Company, Inc.,incorporation of New York No Drawing- Application mm 15, 1935,

Serial No. cases 11 Claims. (in. 195-6) The present invention relates toimprovements in the bating and dehairing of skins and hides.

In dehairing and bating skins and hides, the

usual process has been to employ an'alkalilsuch as lime, and/or sulfidematerials, such as calcium or sodium sulfide for changing the condition.of the skin or hide so that the hair may be readily removed therefrom.The dehairing operation is followed by a bating operation involving theutilization of an infusion or extraction of dung, such as dog dung orpigeon dung.

Dehairing and bating respectively involving the successive utilizationof alkali and/or sulfides and of dung infusions were particularlydiflicult to control, and there was always a possibility of spoilage orserious deterioration of the skins or hides. In addition these processesinvolving sulfides' and also involving unpleasant smelling andodoriferous dung materials create unsanitary l0 and unhealthy workingconditions which greatly increase expense and difliculty of production.

It has been suggested that the bating and/or dehairing of skins andhides might be accomplished by the use of enzymes, but considerabledifliculty was encountered in controlling the bating or dehairing actionwhen both were caused to take place simultaneously and/or in the'samebath, and particular difficulty was experienced in obtaining a uniformand high quality product without considerable skill and exactingcontrol.

An object of the present invention is to provide a dehairing and batingprocess of skins and hides which will provide skins and hides ofimproved quality and characteristics and according to whichsubstantially the same enzymatic liquor may be utilized for both thedehairing and bating operation under accurately determinable andcontrollable conditions.v j

It has now been found that skins and hides may be successively dehairedand bated by the same enzymatic materials provided the conditions of thedehairing and/or hating operation are carefully controlled withresultant enhancement of the possibility of controlling the quality andcharacterof the skins and hides dehaired and bated.

It has been further found that bacterial enzyme preparations, as well asother similar enzyme preparations, such as may be derived from fungiand/or molds, may be prepared in such compositions and utilized undersuch conditions that it is readily possible to obtain a successivedehairing and hating reaction with resultant pro- 55 duction of hidesand skins of very high quality,

which reaction may be most exactly and definitelycontrolled.

Among the preferred enzymatic materials which may be utilized in thisconnection are bacterial enzymes, such as produced by the growth andpropagation of various types of bacilli, particularly Bacillus subtilisand Bacillus mesentericus.

With these bacterial enzyme solutions may be combined or may be includedother enzyme materials, such as those derived by the propagation andgrowth of Aspergillus oryzae, and/or niger. Penicillium glaucum, Mucordelemar, Tryotria: tennis or Amylomyces rowrii, and so forth. Pap ibromelin, trypsin and pancreatin may also be added, if desired.

The dehairing and bating liquors containing these bacterial enzymesshould be in sterile condition and substantially devoid of any livingmicro-organisms and particularly devoid of living bacteria, fungi andferments, and they most desirably may contain small amounts of organiccompounds of disinfectant nature, such as pine oil, phenols, cresylicacids, and naphthols.

In using the bacterial enzymatic or combined enzymatic liquorssuccessively to dehair and bate the skins and hides, it is foundpreferable to first treat the skins and hides with alkali, preferablywith N/8th to N/lOth sodium hydroxide solution.

In the treatment 100 parts of dried weight of goat skins or 200 poundsfresh or salted weight of sheep skins or calf skins may be placed in abath containing about 800 parts by weight of water and about 4 to 6parts by Weight of sodium' hydroxide- The alkali is permitted to swellthe skins or hides ata gradually decreasing temperature, for example,ranging from 90 F. down to F., and preferably from 86 F. down to F., andthe skins or hides are preferably left in the alkali for more than twodays and in some cases four, five and so many as tendays having beenfound satisfactory. I

' After the alkali treatment, and preferably without the intervention ofmore than twenty four hours, the skin or hide should be Washed withwater until preferably it has an alkalinity ranging from pH 10 to 11.The washing in any case should preferably not be carried out to retedand/or the skins or hides may be partly neutralized with solutions ofborax and/or with solutions of sodium bicarbonate.

In preparing the dehairing bath about 5 to 10 parts of the bacterialenzyme solution are utilized for every 100 parts of the skin and theskins or hides are placed in the enzyme solution be tween 12 to 36 hourswith a preferred time of about 24 hours. The temperature is usuallypermitted to fall during the dehairing treatment with the solution,temperature of 36 C. being permitted to gradually decrease to 25 C.sothat the enzyme solution is at a substantially lower temperature atthe termination of the treatment with the dehairing bath, than at thebeginning of such treatment.

It is found satisfactory to add to these dehairing baths ammonium salts,such as ammonium borate and ammonium sulfate, or the salts of reducingsulphur acids, such'as sodium hydrogen sulfite or both together and alsoin certain instances, urea.

Small amounts of suitable organic disinfectants may also be added toexclude any bacterial growth. After removal of the skins or hides fromthe dehairing bath they are subject to mechanical dehairing operationsand various washing operations, if desired, and then preferably duringthe same day or within twenty-four hours the skins or hides are placedin a bating bath which is most desirably weaker in enzyme than thedehairing bath and which preferably contains between to of the enzymestrength as the dehairing bath.

Preferably the pH of the bating bath is substantially less than the pHof the dehairing bath by at least one unit and preferably by two orthree and a preferred pH range is between 7 to 8 or more, desirably 7.3to 7.6.

Sometimes ammonium salts, such as ammonium chloride or sulfate may alsobe added to reduce the pH. Urea and/or sodium bisulfite may also beadded.

In order to exclude unwanted bacterial action, small amounts of suitableorganic disinfectants may also be added. The skins or hides arepermitted to remain in the bating bath for between seventeen totwenty-four hours, and the bath may be permitted to cool during thistreatment with the result that its temperature at the conclusion of thetreatment can be less than its temperature at the beginning of thetreatment.

The hating bath is preferably prepared by strengthening up a previouslyused bating ba with a minor proportion of a freshly prepared bating bathcontaining the constituents above referred to. The enzymaticconstituents are not destroyed by one bating operation and may becontinuously reused, provided the growth of any micro-organism isprevented by the addition of suitable organic substances of disinfectingnature.

As stated above, the preferred enzyme preparatlons include enzymaticliquors produced by the action under aerobic conditions of bacteria orbacilli of the mesentericus or subtilis group upon carbohydrate andprotein containing mediums which liquors are utilized as the enzymepreparations in the dehairing process after suitable quantities of theenzyme have formed therein and after substantially all living bacteriaand other living organisms have been killed and/or carbohydrates,ammonium salts and mineral constituents, such as salts of potassium,magnesium and calcium and phosphates.

Mediums of this character may be prepared, as for example, by treatingor hydrolyzing bran, wheat, or soya bean materials with sulphuric acidand then filtering, and to these nutrient mediums would be added any ofthe desired mineral constituents which are not present.

The nutrient medium is then preferably neutralized to a pH of between7.5 to 9.5 and preferably about 8.5 and it is then sterilized, as forexample, with steam under pressure and at 140 C. for 35 minutes. Y

After the liquor has been sterilized and its pH has been reduced toabout 6.2, it is inoculated with a pure culture of the bacillus of themesentericus or subtilis families. The culture is allowed to develop ator about room temperature or slightly thereabove, and in one instance atemperature of 30 to 40 C. was found most satis- The antiseptic must bemost carefully selected so as not to disadvantageously affect therelatively delicate enzymatic products formed and at the same time mustbe controlled so that it will assure that there will be no livingbacteria present nor any living micro-organisms.

Among the preferred antiseptics which may be employed, preferably incombination are phenol, cresylic acid, beta-naphthol, and other phenolderivatives and preferably consisting of the hydroxylated compounds ofmono or poly-alkylated benzenes or of naphthalunes, which may also behalogenated.

The enzymatic liquor which is preferably filtered from insolublematerials contains the proteolytic enzymes and usually desirably alsoamylolytic and lypolytic enzymes, and in addition metabolicdecomposition products of the proteins and carbohydrates, particularlyvarious hexoses, polysaccharides, dextrines, amino acids, peptones,albuminoids, inorganic and organic phosphates, and so forth.

This liquor may be treated to produce the essential enzymatic andmetabolic materials in concentrated form by -precipitating with alcoholsor various other organic solvents and/or with salt solutions, such asammonium sulphate solutions, in order to obtain the desired ingredientsin solid form.

In the preferred process of the present invention it is desirable thatboth the dehairing and hating be sterile and contain antiseptic agentsto prevent putrefaction and the growth of undesirable micro-organisms.The dehairing action is desirably carried out until the hair is looseand may be readily removed and the subsequent treatment in a bating bathis generally at a decreased pH and enzymatic strength.

Many other changes could be effected in the particular features ofprocess treatment disclosed, and in specific details thereof, withoutsubstantially departing from the invention intended to be defined in theclaims, the specific description herein merely serving to illustratecertain elements by which, in one embodiment, the

liquors. containing antiseptic agents to prevent putrefaction, whichcomprises subjecting the skins and hides to successive treatments inbacterial enzyme baths of decreasing pH value and of decreasingenzymaticstrength, the first treatment being sufiicient to loosen thehairs and enable ready removal thereof.

3. A process of dehairing skins and hides,

which comprises first treating the skins and hides with an alkalisolution and then successively treating them in bacterial'enzymaticbaths containing antiseptic agents to prevent .putrefaction, said bathsbeing of decreasing enzymatic strength and of decreasing pH values, thefirst treatment being sufiicient to substantially loosen the hairs'andenable ready removal thereof.

4. A process of successively dehairing and bating skins and hides withproteolytic enzymatic I liquors containing antiseptic agents to preventputrefaction, which comprises subjecting the skins and hides tosuccessive treatments in proteoiyticenzymatic baths of decreasingenzymatic strength the first treatment being sufllcient to loosen thehairs and enable ready removal thereof.

5., A process of successively dehairing and batingskins and hides withproteolytic enzymatic liquors containing antiseptic agents topreventputrefaction, which comprises subjecting. the

skins and hides to a swelling treatment with an alkali and then 'tosuccessive treatments in proteolytic enzymatic baths of decreasingenzymatic strength, the first treatment being sumcient to vloosenthefhairs and enable ready removal thereof.

. 6.. Afiproc'ess oi successively dehairing and bating skins and hideswith proteolytic enzymatic liquorslcontaining" antiseptic agents toprevent putrefaction, which comprises subjecting the skins and hides tosuccessive treatments in proteolytic-enzymatic baths of decreasingenzymaticstrength the first. .treatment being suflicient to loosen thehairs and 'oI saidsuc enable ready removal there- A tments each beinginitiated I cresyiic acids and naphthols.

at a higher temperature than room temperature, and the temperature ofthe bath being permitted to fall to room temperature during continuationof the treatment. I

7. A process ofsuccessively dehairing and batingskins and hides withproteolytic enzymatic liquors containing antiseptic agents to preventputrefaction, which comprises subjecting the skins and hides tosuccessive treatments in proteolytic enzymatic baths of decreasingenzymatic strength, the first treatment being suiilcient to loosen thehairs and enable ready removal thereof, the hides and skins beingpermitted to remain in said enzymatic baths ior, between 12 to 36 hours.

8. A process of successively dehairing and betting skins and hides withbacterial enzymatic liquors containing antiseptic agents to preventputrefaction, which comprises subjecting the skins and hides tosuccessive treatments in at least two bacterial enzymatic baths ofdecreasing enzymatic strength, the first treatment being suflicient toloosen the hairs and enable ready removal thereof, said first bath usedbeing maintained at a pH of between 10 and 11 and said second bath usedbeing maintained at a pH oi between 7 and 8. a

9. A process of successively dehairing and bating skins and hides withproteolytic enzymatic liquors containing antiseptic agents to preventputrefaction, which comprises subjecting the skins andhides tosuccessive treatments in at least two proteolytic enzymatic baths ofdecreasing enzymatic strength, the first treatment being sufllcient toloosen the hairs and enable ready removal thereof, said second bath usedcontaining an ammonium salt.

10. A process of successively dehairing and bating skins and hides withproteolytic enzymatic liquors containing antiseptic agents to preventputrefaction. which comprises subjecting the skins and hides tosuccessive treatments in at least two proteolytic enzymatic bathsofdecreasing enzymatic strength, the first treatment being sumcient toloosen the hairs and enable ready removal thereof. said first bath usedcontaining an ammonium salt.

11. A process of successively dehairing and hating skins and hides withproteolytic enzymatic liquors containing antiseptic agents to preventputrefaction, which comprises subjecting the skins and hides tosuccessive treatments in proteolytic enzymatic baths of decreasingenzymatic strength, the first treatment being suflicient to loosenthehairs and enable ready removal thereof, said baths eachcontaining oneof a group of disinfectants consisting of pine oil, phenols LEOWALLERSTEIN. JULIUS PFANNMULLER.

